Turntable speed governor



Feb.- 24; 1942. CVB, DALE TUNTABLE lSPEED GOVERNOR 2 Sheets-Sheet 1Filed OCb. l24, l941- Feb. 24, 1942. c. B. DALE TURNTABLE SPEED GOVERNORFiled oct. 24, 1941 2 sheets-sheet 2 Patented Feb. `24, 1942 .UNITEDSTATES PATENT ori-uca.

TURNTABLE SPEED GovEaNoa Y Coun a. nale, oak Park, m., assignma risicoRadio and Television Corporation, Philadelphia; Pa., a corporation o!Delaware Application october 24, 1941, serial No. 416,418

(ci. 'J4- 206) 11 Claims.

t This invention relates to self-governing drive means for turntables.More particularly, the

, invention has reference to such drives useful in.

`combination recording and reproducing phonographs, which drives inaddition utilize a small wheel engaging the inner edge of Ia dependingturntable iiange. l

In recent years there has been a growing demand for home phonographscapable of recording records as well as reproducing the same, and thishas led to certain problems in connection with the phonograph drivemeans. It is desirable to keep such instruments relatively inexpensivein price, and for this reason` they are often supplied-with an inductionmotor, ,as such motors are comparatively economical to construct. n

However, experience has shown that inexpensive turntable drives,especially when powered by the above type of motor, may not be entirelysatisfactory as the motor is incapable of driving the turntable at anunvarying .speed from start to finish of a record, particularly dur-.ing the recording operation. During recording,

there is a wide variation in the number of inch- 'ounces of resistiveeffort exerted by the cutting stylus between its positions at thebeginning and tional speed, regardless of variations in the forceapplied to the turntable, or the lever arm through which this. force isacting.

yIt is a more particular object of this inventiony to provide, in aphonograph drive mechanism;y

of the type utilizing a wheel driven from the' face of a disc, a movablymounted shaft arranged to move said wheelto a disc area of highersurface speed, in response to an increase in the load upon theturntable.

A further object of the present invention resides inthe provision of agovernor mechanism of the above type which is lsimple to construct andpositive in its action, being. responsive to very minute iluctuations inturntable speed.

The manner in which the' above and other objects and advantages arerealized will be best` understood by considering the followingdescription taken with the accompanying drawings, in

which:

Fig. 1 is a side elevational view of a phonograph drive mechanismincorporating the present invention; v

`Fig. 2 is a top plan view of the mechanism shown in Fig. l, with theturntable and base-- plate shown in dot-and-dash outline:

Fig. 3 is' a sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is a detail sectional view on a larger scale of a portionA ofthedrive mechanism; and Fig. 5 isa detail sectional viewtaken along line 55 of Fig. 4.

.Referring moreparticularly to the drawings, Fig. 1 illustrates theessentials of. one form of drive mechanism with which this invention isespecially useful.

This mechanism comprises a-'main-baseplate l having aV central recessedportion 2 to accommodate the conventional turntable 3, which may bemounted for rotation about a central spindle 4 by means of a suitablebearing (not shown). The cooperating tone arm and amplier may be anywell known type, and hence need not be here illustrated or described.

Beneath the baseplate i, a pair of depending arms 5-5 are pivotallyconnected to a pair of apertured lugs- 6 6, formed on a generalLvhorizontal. bracket 1. `A constant speed electric motor l carrying adriving disc 9, is supported on bracket 1, as by semi-resilient mountingblocks ill. A generally bell shaped wheel li is -in driven engagementwith the face of disc I,

and is attached to a short shaft I2 (see Fig. 4), which carries a smallturntable driving wheel i3 atx/its upper end. 'I'his wheel is preferablymade voffrubber, or some other suitable irictional material. 'I'heconstruction and 'mounting of memf bers Il, i2 and I3 will be fullybrought out herematter.

'I'he arrangement of disc 9, wheel il and bracket 'I -is suchvthat thespeed of rotation of the turntable 3 will be determined by the point ofcontactA between the disc and its cooperatingwheel, that is, the'greaterthe driving radius of disc 9 the greater the turntable speed.

In the embodiment illustrated, the turntable speed is not onlyautomatically regulated' in .a' manner to be hereinafter described, butis manu- `ally adiustable. by raising or lowering the bracket 1. Thisadjustment is effected by rotating the control knob Il, which serves tooscillate -pending application of Elmer O. Thompson,

Serial No. 412,654 led September 27, 1941.

As is best shown in Figs. 2, 4 and 5, shaft -I2, which carries wheels IIand I3, is supported in a novel manner now to be described. Bracket 1 lcarries a small U-shaped member I1 which in turn carries a bearing blockIll, pinned -to bracket I1 by a pivot member I9. The lower end of shaftI2 is mounted for rotation in block I8 by means of a bearing insert 20.'As will be apparent from.

the drawings, this assembly provides a main pivot point about whichvthelongitudinal axis of shaft I2, and its associated wheels II and I3, mayswing, thereby varying the effective driving radius of disc 9, asindicated in Fig. 1. Bracket 1 is apertured at 2I to accommodate thelower end of shaft I2. This is necessary when the bracket 1 is capableof manual adjustment, in accordance with said copending Thompsonapplication.

Making particular reference to Figs. 2 and 4, it will be seen that theupper end of shaft I2 is supported by a lever 22, pinned to thebaseplate as at 23, by means of an elongated aperture 24 formed in' saidlever. The lever is urgedoutwardly from pivot 23 by means of a spring 25fixed to a lug .on the baseplate, as at 26. At its free end, lever 22has a cup-shaped depression 21 (Fig..4) through which the shaft I2passes. A bearing 28 is seated in the cup 21, and is prevented fromrotating by means of a lug 29, which extends into a recess in bearing28. Washers 30 and 3I serve to maintain the proper relationship of theabove described bearing elements, mounting the shaft for rotation, whilestill permitting a slight rocking of shaft I2 as the lever 22 swingsabout its pivot 23. Wheel I3 and collar 32 (held by set screw 33)cooperate to maintain the abovedescribed elements in assembled relationand to .prevent longitudinal movement of shaft I2 relative to lever 22.

A second spring 34, is' provided, and is adjustably xed to the baseplateat 35. A pair of stop members 36 and 31 (the last named being providedwith an eccentric pivot to provide adjustability thereof) -limit theangular movement of lever 22 to a desired range, and as will be seenfrom Fig. 2, the two spring members move lever 22 in a direction tourge-wheel I3 into rm contact with the inner edge of the dependingturntable flange.

The operation of the device is as follows:

With the direction of turntable and driving wheel rotation as shown inFig. 2, wheel I3 will tend to move around the edge of turntable 3 (inresponse tothe resistance to rotation presented -by the turntable and`its cooperating stylus) in a direction .to move lever 22 toward stop 31.The position of the parts shown in Fig. 2, with the lever closelyadjacent stop 36,'-is the no-load condition. When the stylus is placedupon the record, wheel I3 will move somewhat, as above described,against the tension of spring 34 and assume a balanced position; betweenstops 36 and 31. The screw 38 provides readyadjustability of the tensionof spring 3l, and thereby ensures that lever 22 will find its properbalanced position. Upon a sudden variation in the resistive eiortexerted by the stylus, turntable 3 will tend to slow down or increaseits speed, as the case may be, and wheel I3 will seek a new position. Asbest seen in Fig. 1, this movement of wheel I3 will cause shaft I2 toswing about its lower pivotv I9, thereby changing the position of wheelII with relation to disc 9. The relation of the rotating parts, and thedisposition of pivot I9, is such vthat movement of wheel I3 towardeither of stops 36 and 31 will move wheel 'I`I in a direction to restorethe proper speed of turntable 3. For example, increases in the resistiveload presented by the turntable, will rst cause a minute diminution ofits speed, thereby 'causing pulley I3 to move toward stop 31, movingshaft I2 to the dot-and-dash position shown in Fig. 1. As is readilyapparent, this increases slightly the effective radius of disc 9 and`restores the desired speed.

It will be clear from the above that. the invention provides aself-compensating drive, ensuring a substantially uniform turntablespeed, and that the' device is of such a construction that it isresponsive vto extremely small speedvariations, thereby ensuring aconstant .speed within unusually close 1imits.

In addition, the mechanism has the advantages of simplicity and lowcost, and may be readily assembled or adjusted.

The device disclosed may be used on either manual or automaticphonographs, and in addition, -although illustrated with a single speeddrive, may be readily modified for application lto phonographs capableof operating at two different speeds. It will be understood, therefore,that the invention is susceptible of modication within the scope of theappended claims.

I claim: l

l. A drive mechanism forA operating 'a turntable at a desired speed.comprising a driving element frictionally engaging the turntable; meansmounting said element for translational movement in response tovariations in speed of the turntable, and variable speed drive means forsaid turntable responsive to the translational movement of said elementfor restoring the desired speed of the turntable.

2. A drive mechanism for operating a turnl table at a desired speedcomprising a driving element frictionally engaging the turntable andarranged for translational movement in response to variations in speedof the turntable, a variable speed driving means for ythe turntable. andmeans responsive to the translational movement of said element foradjusting said driving means so as to restore the desired speed of theturntable.

3. A drive mechanism for operating a turntable at a desired speedcomprising a rotary driving element operatively associated with theturntable to drive the same and arranged for translational movementgenerally parallel to the rotational plane of the turntable in responsetovariations in speed of the turntable, a variable speed driving meansfor the turntable, and means re'- sponsive to the translational movementof said element for adjusting said driving means so as to restore thedesired speed of the turntable.

4. In a transmission having a turntable and a substantially constantspeed motor, a selfregulating drive mechanism providing speed controlfor said turntable, said mechanism comprising a rotatable element'drivenby said motor and having driving zones of differing surface speeds; asecond rotatable element ir driven engagement with the driving surfaceof said first element, and means operatively associated with said secondelement and in driving contact with said turnaavaoaa n ratio betweensaid first and second elements, to

table, said last means being constructed and arranged to move therotational axis of said second element in response to load variations onthe turntable, thereby varying the point of contact between said firstand second elements to com pensate for variations in drag and resultantspeed changes of said turntable.

5. In a transmission having a turntable and substantially constant speedmotor, a self-regulating drive mechanism providing speed control forsaid turntable, said mechanism comprising a rotatable element driven bysaid motor and having driving zones of differing surface speeds, asecond rotatable element in driven engagement with the driving surfaceof said rst element, a shaft fixed to said second element and in drivingycontact with said turntable, and means mounting said shaft forrotational movement about two different axes, said last means beingmechanism comprising a rotatable element driven by said motor and havingdriving zones of differing surface speeds, a second rotatable elementndriven engagement with the driving surface of said first element. arotatable shaft xed to said second element and carrying a driving memberc contacting a face of the turntable flange, and means mounting saidshaft for pivotal movement about an axis intersecting its normalrotational axis, said last means being adapted automatically to effectsuch pivotal movement in response to variations in the load on. theturntable, thereby varying the driving ratio between said iirst. andsecond elements to compensate for variations in drag and resultant-speed changes of said turntable.

7.1 I n a transmission having a circumferentially flanged turntable andamotor, a self-regulating compensate for variations in drag andresultant speed changes of said turntable.

8. In a transmission having a circumferentially flanged .turntable and amotor, a self-.regulating drive mechanism providing speed control forsaid turntable, said mechanism comprising a rotatable element driven bysaid motor and having driving zones of differing surface speeds, asecond rotatable element in driven engagement with the driving surfaceof said first element, a rotatable shaft adapted to be driven by saidsecond element and in driving engagement with a face of the turntableflange, means mounting said shaft for pivotal movement about an axisintersecting Yits normal rotational axis to vary the zone of contactbetween said first and second rotatable elements, and means formaintaining the driving engagement of said shaft with said ilange duringmovement of said shaft about said intersecting axis.

9. In a phonograph having a turntable and a motor, a self-regulatingdrive mechanism providing speed control for said turntable, said mecha.-

nism comprising a disc driven by said motor, a

rotatable element in driven engagement with the surface of said disc,drive means xed to said rotatable element and extending between saidelement and said turntable, said drive means having a longitudinal axisnormally disposed in predetermined relation tothe plane of rotation ofsaid disc, and lmounting means for said drive means arranged to eiectrotation of the longitudinal axisA of said drivel means to vary the`driving radius of said disc, in response to variations in the speed ofrotation of said turntable:

l0. A construction in accordance with claim 9,

' wherein said mounting means comprises a pair a pivot for therotational movement of the longi- 4to limit and control the movementabout said v drive mechanism providing speed control for. said lturntable,.said mechanism comprising a rotatable element driven `by saidmotor and having driving zones of differing surface speeds, a second'rotatable ,element in driven vengagement with the driving surface yofsaid ilrst element, a lrotatable shaft adapted to ibe driven by saidsecond element and carrying a driving 'member'. means urging saiddriving member into contact with the inside face l of the turntableflange, and means mounting said `shaft for pivotal movement about anaxis intersecting lts normal rotational axis, said last means beingadapted to automaticalLv effect such pivotal movement in response, tovariations in the load on 'thetumtabIe and t9 thereby vary the drivingof spaced apart bearings, one of which serves as tudinal axis of s aiddrive means, andthe other of which is carried by a pivoted arm whichservespivot. n

1l. In phonograph turntable driving means, a

' main baseplate, a member having one end thereof pivotallyl secured tosaid baseplate, a driving element mounted for rotation in the free endof said pivoted member, a pair of driving wheels tlxedly secured to saiddriving element in spaced relation, one of said wheels being 'adapted todrive the turntable through a flange thereon, and the other of saidwheels being adapted to be motor driven, a pair of stops limiting theangularmovement of said member about its pivot, means urging said membertoward one of said stops, means urging the turntable driving wheel intocontact with the flange of said turntable, and pivot means mounting saidshaft for limited rotational movement about an axis intersectingits-normal rotational axis.

COLIN B. DALE.

